<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="../bootstrap/css/bootstrap.min.css">
    <style>
        .row div{
            border: 2px solid red;
        }
    </style>
</head>
<body>
    <div class="container">
        <!-- 通过类标签来表示其占12列的份数 大屏幕：col-lg-份数 -->
        <!-- 大屏幕：col-lg-份数  屏幕：col-md-份数 平板：col-sm-份数 手机：col-xs-份数 -->
        <!-- lg = large  md = medium  sm = small xs = extra small -->
        <div class="row">
            <div class="col-lg-3 col-md-4 col-sm-4">1</div>
            <div class="col-lg-3 col-md-4 col-sm-4">2</div>
            <div class="col-lg-3 col-md-4 col-sm-4">3</div>
            <div class="col-lg-3 col-md-4 col-sm-4">4</div>
        </div>
        <!-- 如果孩子的份数相加等于12, 则孩子能占满整个container的宽度 -->
        <div class="row">
            <div class="col-lg-6">1</div>
            <div class="col-lg-2">2</div>
            <div class="col-lg-2">3</div>
            <div class="col-lg-2">4</div>
        </div>
        <!-- 占不满 -->
        <div class="row">
            <div class="col-lg-6">1</div>
            <div class="col-lg-2">2</div>
            <div class="col-lg-2">3</div>
            <div class="col-lg-1">4</div>
        </div>
    </div>
</body>
</html>